Foods have been smoked, since humans first used fire to prepare meals, to provide flavor, color, and preservation. Initially, preservation was the ultimate reason to smoke foods, but as food preservation techniques advanced, flavor and color became the main reasons to smoke foods. As societies became more industrialized, the shift from home or individual smoking to processing in specialized plants led the need for improved control of smoking procedures, including consistent smoke application techniques.
Consequently, liquid smoke compositions (also known as liquid smoke solutions, and colloquially referred to as liquid smokes) were developed as a replacement for smoking of food by direct contact with smoke in a smokehouse. Such compositions have become a standard industry practice.
When applied to the surface of meats and other proteinaceous foodstuffs, such as various types of sausages, frankfurters, bolognas, beef rolls, hams, and the like, liquid smoke gives the item a characteristic smokey flavor and produces a dark smoked color. The achievement of a smokehouse-like product by application of an aqueous smoke solution to a foodstuff requires control and balancing of many variables such as the food composition, temperature, humidity, processing time, contact time, amount of liquid smoke, and concentration of liquid smoke.
It is well known to those skilled in the art that liquid smoke compositions contain a wide array of chemical compounds, and over 400 such compounds have been identified. Nevertheless, it is also well known to those skilled in the art that liquid smoke compositions are characterized by their content of certain classes of compounds, namely, acids (% titratable acidity), phenols, and carbonyls.
The acids are preservatives, and, of course, pH control agents, as a result of which commercial liquid smoke compositions typically have a pH under about 2.5, and more typically under about 2.3, and a % titratable acidity by volume from about 3% to about 18%. The phenols give flavor, and also aroma, to liquid smoke compositions, and commercial compositions typically have a phenols content from about 10 to about 45, and more typically, from about 14 to about 30 mg/ml. The carbonyls impart the brown color to liquid smoke compositions. The phenols and the carbonyls can be measured as described in the below-mentioned U.S. Pat. No. 4,431,032 to Nicholson. The browning potential of liquid smoke compositions can be measured by the well-known in the art Browning Index procedure described in the below-mentioned U.S. Pat. No. 4,994,297 to Underwood or by the well-known in the art Staining Index procedure involving reaction of liquid smoke with glycine. It is noted that the acids and carbonyls are secondary in contributing to the flavor of liquid smoke compositions. The color value can be measured as described in the below-mentioned U.S. Pat. No. 5,681,603 to Underwood. The'603 Patent to Underwood also describes how to measure B(a)P, which is carcinogenic and thus should be under 10 ppb.
As general background, improved liquid smoke compositions and techniques for their manufacture are described in U.S. Pat. No. 4,154,866 to Dainus, Dane, and O'Hara (assignee Stange Co.) and U.S. Pat. No. 4,994,297 to Underwood (assignee Ensyn Engineering Associates, Inc.).
As the advent of liquid smoke compositions has significantly improved meat processing, attempts have been made over the last 20 years or so to deal with the precipitate problem of liquid smoke. Upon storage of a liquid smoke product, the precipitate settles out forming a water insoluble, sticky, viscous residue on the bottom of the container for the liquid smoke.
Furthermore, even though liquid smoke is aqueous, liquid smoke is not totally water soluble, which exacerbates the precipitate problem. More specifically, the precipitate will occur upon dilution of liquid smoke with water.
Nevertheless, the precipitate can be kept in emulsion. For instance, U.S. Pat. No. 4,442,868 to Smith and Kearby (assignee Teepak) discloses the treatment of liquid smoke with alkaline agents to a pH of 10 or higher to dissolve precipitates so they stay in solution and to produce a coloring/flavoring agent for casing use. Moreover, not only does U.S. Pat. No. 4,446,167 to Smith and Kearby (assignee Teepak, Inc.) disclose the formation of a basic smoke flavorant/colorant from natural wood smoke, along with food casings and food products utilizing the flavorant/colorant, but also this U.S. patent is closely related to the disclosure of '868 to Smith and Kearby. Also, as described in U.S. Pat. No. 5,690,977 to Hammer, Mans, and Winter (assignee Hoechst AG), disclosed is a modified liquid smoke solution that contains an unmodified aqueous liquid smoke solution and an alkaline neutralizing agent. The composition also includes a synthetic or natural oil, a viscosity increasing component and one or more emulsifiers. The liquid smoke mixture is disclosed as containing the alkaline neutralizing agent in an amount such that the mixture has a pH of about 8 to about 14, and preferably of about 8.5 to about 12.
Alternatively, the precipitate can be removed, which may be achieved by a solvent extraction process used on liquid smoke to create a desirable tar-depleted liquid smoke supernatant fraction and an undesirable tar-containing fraction, followed by gravity separation of the two fractions, as is described in U.S. Pat. No. 4,431,032 to Nicholson (assignee Union Carbide Corporation). Also, U.S. Pat. No. 4,604,309 to Goldberg (assignee Teepak, Inc.) discloses a method for producing a liquid smoke solution which includes the step of neutralizing liquid smoke with a base such as sodium hydroxide to a pH of 6 to 7, which causes tar to precipitate. The precipitate is discarded. The aqueous portion can be extracted with organic solvents before or after treatment with the base. Furthermore, U.S. Pat. No. 4,834,993 to Chiu (assignee Viskase Corporation) discloses a liquid smoke solution that is prepared by precipitating tars via neutralizing an acidic liquid smoke composition followed by subsequent discarding of the tars. The neutralized liquid smoke composition preferably retains a pH of 5 to 9. Additionally, U.S. Pat. No. 5,637,339 to Moeller (assignee Hickory Specialties, Inc.) discloses treating liquid smoke with activated carbon particles to remove tars and create a tar-depleted liquid smoke that is totally water miscible.
Of more particular interest in relation to the present invention is the process of U.S. Pat. No. 4,278,694 to Chiu (assignee Union Carbide Corporation), which discloses methods for preparing aqueous liquid smoke compositions, including a concentrated aqueous liquid smoke composition. The concentrated aqueous liquid smoke composition is prepared by substantially neutralizing a liquid smoke solution containing smoke coloring and flavoring constituents to a pH of greater than about 4 with an alkaline neutralizing agent to form a precipitate of smoke tars. The smoke tars precipitate is then separated from the supernatant liquid and is then subsequently dissolved in a water soluble alcohol solubilizing agent to form a smoke tars liquid smoke composition having greater than about 15% by weight of dissolved smoke tars. The stated pH range for neutralized compositions is from about 4 to about 8. The precipitate is derived from a substantially unrefined liquid smoke source and thus includes a high concentration of tars, including high levels of undesirable components of tar, including benzo(a)pyrene, now known to be a carcinogen. An improvement is shown in the more recent U.S. Pat. No. 5,681,603 to Underwood (assignee Red Arrow Products). More specifically, Underwood discloses making a coloring/flavoring composition by contacting water insoluble tar by-product (from liquid smoke) with an alkaline solution to an end pH above 10. The tar solution is then contacted with certain non-ionic aromatic hydrocarbon-based resins to reduce the benzo(a)pyrene content to 10 ppb or less.
The disclosures of all of the above-mentioned patents are incorporated herein by reference.
Despite the above-discussed procedures to use the removed precipitate components of liquid smoke (such as using tar as described in '694 to Chiu and '603 to Underwood), nevertheless, problems still exist with such procedures. For instance, the process of '603 to Underwood has a shortfall in that the process includes a time-consuming contact step with the resin to remove the carcinogenic benzo(a)pyrene.
Thus, it is desirable to find an improved liquid smoke composition that is made from precipitate and a method for the manufacture thereof, which composition and method obviate the above-mentioned problems.